Field of the Invention
The invention relates to telecommunication devices, and, more particularly, to a neck-wearable telecommunication device.
Description of the Related Art
Wearable telecommunication devices based on a necklace, collar, neckband, headband or other similar load-carrying structure are often used as an interface between a human being and a technical system, which may be a telecommunication system, a computer system, an entertainment system, a medical system, a security system, etc.
Known stereo headsets in the form of a necklace, collar, neckband, either a neck half-loop or a neck loop type, have predominantly two types of connection between earphones and the neck part: headsets with two side nodes, in which earphone cords are connected with the neck part and do not have connections between themselves, and headsets with a single node, in which earphone cords are connected to each other and to the neck loop in a single node.
A conventional headset (see U.S. Pat. No. 7,416,099B2) includes earphones connected through cords to a supporting structure, which accommodates a signal transceiver, and is connected to a necklace (neck loop). The headset comprises long unsecured portions of cords connecting the earphones to the neck loop, because the additional length is needed when the user rotates and moves the head relative to the torso. The headset has two nodes and the length of the movable portion of the cords in the headset is more than 19 cm. The cords hang freely along the entire length thereof in the air over the user's body surface, so they have slack and might tangle and cling to surrounding objects. In addition, the headset is difficult to wear under clothing, both in the operational and non-operational position, i.e., when the earphones are taken off the ears.
A known earphone storage structure (U.S. Pat. No. 7,936,895B2) includes a necklace (similar to a neck loop), two fasteners formed in the two ends of the necklace, and stoppers. The size of the fasteners is smaller than the size of the stoppers and the size of the earphones, therefore the earphones may be pulled out when they are not used. The stoppers connection form nodes, and this device relates to headsets with two side nodes. The earphone storage structure has the same limitations as the previous device: cords have slack, and the structure is difficult to wear under clothing, and managing it through clothing is not convenient.
A lanyard for a portable electronic device (U.S. Pat. No. 7,650,007B2) includes two side connection nodes and allows adjusting the length of earphone cords, but the lanyard does not eliminate sagging of cords in the operational position.
In a necklace-type audio device (WO 2012015257A1), earphone cords form a neck loop when they are attached at their ends to a jack disposed on the user's chest, and crossed through two rings disposed in the back of the necklace (neck loop), the rings being adapted to adjust the length of the neck loop and earphone cords. In this device, the length of the cords connecting the earphone to the necklace (neck loop) is even longer than in necklace-type headsets with two side nodes; this contributes to slacking the cords, and the way of adjusting the length of cords in the headset eliminates a possibility of wearing the device under clothes.
A known modular personal audio device (WO 2005022872A1) and (US 20070021073A1) includes a necklace having a winding device for headphone cords. These cords are connected to the rear part of the necklace and may be coiled when the headphones are in the non-operational position. However when the cords are in the operational position, they are still loose and so remain movable, and freely hang over the user's head during rotation of the head. Hook-type holders are provided for securing the headphones to the auricle. This makes wearing the device noticeable and inconvenient. The device does not have any controls means.
A known headset (US 20020043545A1) includes a headphone and a microphone, the headset provided in the form of a wire loop bearing the device connected to the headset. This makes wearing the headset noticeable and inconvenient. The device does not have any controls means.
A known headset (US 2002065115A1) which includes one or two headphones and one or two microphones, the headset provided in the form of a wire loop bearing the device connected to the headset. The headphones are connected to the device by separate cords. This makes wearing the headset noticeable and inconvenient. The device does not have any controls means.
A known loop (US 20070080186A1) for retaining an electronic device, has cords are located inside the loop, and the user is able to change the point where the cord leaves the loop and to adjust the length of the loose part of the cord by moving a clip. However, this makes wearing the headphones noticeable and inconvenient during rotation of the head.
A known wire loop (US 20070053523A1) for retaining an electronic device, wherein the user is able to adjust the length of the loose part of the cords by moving a clip. However, this makes wearing the headphones noticeable and inconvenient.
A known headset (US 2008143954A1), (US 20110051982A1) is in the form of spectacles comprising headphones to be secured on the spectacle frame when the headphones are in a non-operational position and connected by separate cords to an electronic unit located on the user's occiput. The headset has a considerable weight and the electronic unit observably extends from the user's head surface. This makes wearing the headset noticeable and inconvenient.
A known headset (US 2008283651A1) includes a loop for bearing the headset on the user's neck, headphones and a device for retracting and coiling the cord extending from the headset to an external electronic device which may be placed in a pocket or fastened to a belt, etc. This makes wearing the headphone noticeable and inconvenient. The device does not have any controls means.
A known modular personal audio device (US 2009318198A1) includes headphones connected by separate cords to an electronic unit comprising a power source and located on the user's neck's back side. The separate cords are disposed at the level of lower part of user's auricles, so this makes wearing the device noticeable and inconvenient.
A known wire loop (WO 2003103255A1) for bearing an electronic device, wherein the user is able to adjust the length of the loose part of the headphone cords by moving a clip, and magnets are used to retain the headphones in the non-operational position. However when the user changes length of the headphone cords, size of the neck loop changes correspondingly, and the cords comprise loose parts. All this makes wearing the headphone noticeable and inconvenient.
A known audio player (WO 2009019517A2) aggregated with a rigid headband, wherein an electronic device and control means are disposed in a rear part of the headband located on the back surface of the user's neck. A rigid configuration of the player makes its wearing noticeable and control turns out to be inconvenient.
A known headset (WO 2010019634A2) includes an open rigid loop having a microphone located at one end thereof and headphones connected to the loop by separate cords. A loose part of the cord makes wearing the headphone noticeable and inconvenient. A rigid configuration of the loop is incompatible with certain types of clothes.
Therefore, the conventional devices, first, include excessively long unsecured portions of cords that connect the head part of a headset having a neck loop (in headsets with a single node the length of freely hanging cords is about 19 cm, and in headsets with two side nodes it is about 25 cm) and, second, unsecured portions of cords in the conventional devices do not fit to the body surface. The cord slack cannot be fully removed without restricting the freedom of movement of the user's head. Therefore, when the devices are used, the cords either slack, tangle and cling to surrounding objects, or restrict freedom of the user's movement.
Therefore, no device suitable for constant wearing has been designed up to now, which device would have a small total length of freely hanging cords snugly fitted to the body and creating no impediments to movements of the head. Such a device shall provide improved user experience by facilitating easy use, assuring secure fixation thereof on the user's body, and preventing failures caused by the cords clinging to surrounding objects.
In general, the degree of slack of cords depends on the following factors:                the length of movable portion of cords between fixed points. In all conventional neck headsets this is the length of the cord between an earphone and the neck loop, so the shorter the movable portion of the cord, the less the slack is;        cord tension;        degree of adherence of the cord to the body surface;        position of the cords; cords disposed on a plane do not slack as opposed to cords hanging in the air or lying above natural depressions on the surface of user's body.        
It shall be noted that in the description of the invention herein, a wearable device or a part thereof may be put on the neck of a user and may look like an article of clothing, e.g., a scarf or a neckerchief, which can be put on and used in the form of an O-shaped neck loop or an U-shaped neck loop
In order to concisely indicate a component designed and arranged to be worn around the neck, the following terms may be used: neck loop, neck set, neck strip, neck tape, neckerchief, neck strap, neck band, neckwear, neck-wearable housing, neck sheath, and so on.
The inventor has found by experimentation that the components disposed on the user's neck, shoulders and chest, being both in the form of a closed loop (such as an O-loop) and an open loop (or a half-loop, or a U-shape), equally allowed attaining the same technical result when the neck-worn part of components were properly located adjacent to the dorsal part of the user's neck. In this case, the dorsal and suboccipital nodes of the device are located in optimized positions according to the mathematical models described herein, which is essential for attaining advantageous effects of this invention.
But, from a usability point of view, the two types of neck loops may differ from each other. In particular, an O-shaped loop can hardly be put on and taken off without unfastening thereof. Moreover, this is technically difficult for a typical women-targeted device due to the smaller size of the device. Unfastening the device at the rear side, as it is usual for the most necklaces, is not convenient due to presence of the dorsal node disposed on the dorsal neck side, which is one feature of the invention.
The inventor would like to highlight a wearable device comprising an U-shaped neck-wearable housing as a separate option. This option allows easy put-on and take-off of the device and provides compact design thereof.
A wide range of wearable electronic devices appeared recently owing to development progress in radio engineering and computer engineering. However, the problem of noise reduction in speech signals became even more pressing as the wearable devices may be used in a very noisy environment.
The easiest way of noise reduction in a speech signal is placing a low sensitive microphone in a close vicinity of a user's mouth. But this causes certain usability problems as the microphone is clearly visible and a support structure has to be used in order to fix the microphone in an appropriate position.
Another way of noise reduction in a speech signal is using a dual-port microphone which may be positioned somewhat more distantly from the user's mouth, e.g., on the user's chest. A dual-port microphone facilitates noise cancellation owing to processing two speech signals taken from different directions. However, in order to assure effective noise cancellation by phase and volume processing, the distance between the user's mouth and the microphone ports has to be exactly known, which is impossible when the user tilts and/or rotates his/her head.
Moreover, the user possibly will have to bend his/her head towards the chest in order to maintain acceptable quality of the speech signal in a very noisy environment. According to scientific research, see [1], methods of digital processing a speech signal obtained from a single microphone yielded substantial distortion of the signal and unacceptable separation of speech and noise.
Still another way of noise reduction in a speech signal is digital processing multiple speech signals obtained from a number of microphones aggregated into a microphone array of a certain type. Extraction of a target signal from a signal/noise mixture may be performed using various algorithms based on different mathematical tools. According to scientific research, see [1], the optimal number of microphones in a microphone array was found to be in the range of three to five, as the less number of microphones ceased effectiveness of processing and the greater number of microphones did not contribute in considerably better results.
A noise-reducing directional microphone array is disclosed in WO 2007106399. The array comprises at least two microphones generating forward and backward cardioid signals from two omnidirectional microphone signals. An adaptation factor is applied to the backward cardioid signal, and the resulting adjusted backward cardioid signal is subtracted from the forward cardioid signal to generate a first-order output audio signal corresponding to a beam pattern having no nulls or negative values of the adaptation factor. After low-pass filtering, spatial noise suppression can be applied to the output audio signal. Microphone arrays having one or more additional microphones can be designed to generate second- or higher-order output audio signals.
A mobile telephone with multiple microphones is disclosed in US 2006147063. The telephone is equipped with multiple microphones which provide improved performance during operation of the telephone in a speaker-phone mode. These multiple microphones can be used to improve voice activity detection, which in turn, can improve echo cancellation. In addition, these multiple microphones can be configured as an adaptive microphone array and used to reduce the effects of room reverberation, when a near-end user is speaking, and/or acoustic echo, when a far-end user is speaking.
Eye glasses with a microphone array are known from US 2014278385. The publication discloses a method of reducing noise by forming a main signal and one or more reference signals at a beam-former based on at least two received audio signals, detecting voice activity at a voice activity detector, where the voice activity detector receives the main and reference signals and outputting a desired voice activity signal, adaptively canceling noise at an adaptive noise canceller, where the adaptive noise canceller receives the main, reference, and desired voice activity signals and outputs an adaptive noise cancellation signal, and reducing noise at a noise reducer receiving the desired voice activity and adaptive noise cancellation signals and outputting a desired speech signal.
A device and method for direction dependent spatial noise reduction is disclosed in WO 2011101045. The device includes a plurality of microphones for measuring an acoustic input signal from an acoustic source. The microphones form at least one monaural pair and at least one binaural pair. Directional signal processing circuitry is provided for obtaining, from the input signal, at least one monaural directional signal and at least one binaural directional signal. A target signal level estimator estimates a target signal level by combining at least one of the monaural directional signals and at least one of the binaural directional signals, which at least one monaural directional signal and at least one binaural directional signal mutually have a maximum response in a direction of the acoustic source. A noise signal level estimator estimates a noise signal level by combining at least one of the monaural directional signals and at least one of the binaural directional signals, which at least one monaural directional signal and at least one binaural directional signal mutually have a minimum sensitivity in the direction of the acoustic source.
A noise-reducing directional microphone array is disclosed in WO2014062152. The directional microphone array comprises at least two microphones mounted on opposite sides of a device and generates forward and backward base signals from two omnidirectional microphone signals using diffraction filters and equalization filters. Each diffraction filter implements a transfer function representing the response of an audio signal traveling from a corresponding microphone around the device to the other microphone. A scale factor is applied to, for example, the backward base signal, and the resulting scaled backward base signal is combined with (e.g., subtracted from) the forward base signal to generate a first-order differential audio signal. After low-pass filtering, spatial noise suppression can be applied to the first-order differential audio signal. Microphone arrays having one or more additional microphones can be designed to generate second- or higher-order differential audio signals.
An adaptive noise canceling arrangement, a noise reduction system and a transceiver are disclosed in WO 9723068. The cross-coupled adaptive noise canceling arrangement comprises an adaptive cross-talk filter which is split into a prefilter section and an adaptive filter section, the sections using different input signals. The prefilter section estimates the desired signal from the input signal of the noise canceling arrangement, and the adaptive filter section has its input coupled to the output of the noise canceling arrangement, a delay section being provided between the input and the output of the noise canceling arrangement. The prefilter section and the adaptive filter section are separate filters.
Microphone arrays with rear venting are disclosed in US 2009003640 and US 2012207322. Such a microphone array includes at least two physical microphones to receive acoustic signals. The physical microphones make use of a common rear vent (actual or virtual) that samples a common pressure source. The microphone array includes a physical directional microphone configuration and a virtual directional microphone configuration. By making the input to the rear vents of the microphones (actual or virtual) as similar as possible, the real-world filter to be modeled becomes much simpler to model using an adaptive filter.
An Audio signal processing device is disclosed in US 2015125011. The device includes frequency conversion units configured to generate a plurality of input audio spectra by performing frequency conversions on input audio signals input from a plurality of microphones provided in a housing, a first input selection unit configured to select input audio spectra corresponding to a first combination direction from among the input audio spectra based on an arrangement of the microphones for the housing, and a first combining unit configured to generate a combined audio spectrum having directivity of the first combination direction by calculating power spectra of the input audio spectra selected by the first input selection unit.
A directional hearing system is disclosed in WO 9740645. The system is constructed in a form of a necklace including an array of two or more microphones mounted on a housing supported on the chest of a user by a conducting loop encircling the user's neck. Signal processing electronics contained in the same housing receives and combines the microphone signals in such a manner as to provide an amplified output signal which emphasizes sounds of interest arriving in a direction forward of the user. The microphone output signals are weighted and combined to achieve desired spatial directivity responses. The weighting coefficients are determined by an optimization process. By bandpass filtering the weighted microphone signals with a set of filters covering the audio frequency range and summing the filtered signals, a receiving microphone array with a small aperture size is caused to have a directivity pattern that is essentially uniform over frequency in two or three dimensions.
A super directive microphone array is disclosed in WO 9746048. In the array, analog filters are used to band-limit at least two secondary microphone elements which are spaced from a primary microphone element by a distance respective of their band limited outputs. The band-limited secondary microphone signals are digitized by an analog-to-digital converter. A signal processor performs a super directive analysis of the primary microphone signal and the combined secondary microphone signals. A plurality of microphones may be arranged in a ring. Their outputs are digitized, split into frequency bands, and weighted sums are formed for each of a plurality of directions. A steering control circuit evaluates the relative energy of each directional signal in each band and selects a microphone direction for further processing and output.
A microphone array subset selection method for robust noise reduction is disclosed in WO 2011103488. The method includes selecting a plurality of fewer than all of the channels of a multichannel signal, based on information relating to the direction of arrival of at least one frequency component of the multichannel signal.
A microphone system for teleconferencing system is disclosed in WO 9510164. The system comprises at least two directional microphones, mixing circuitry, and control circuitry. The microphones are held each directed out from a center point. The mixing circuitry combines the electrical signals from the microphones in varying proportions to form a composite signal, the composite signal including contributions from at least two of the microphones. The control circuitry analyzes the electrical signals to determine an angular orientation of the acoustic signal relative to the central point, and substantially continuously adjusts the proportions in response to the determined orientation and provides the adjusted proportions to the mixing circuitry. The values of the proportions are selected so that the composite signal simulates a signal that would be generated by a single directional microphone pivoted about the central point to direct its maximum response at the acoustic signal as the acoustic signal moves about the environment.
A directional microphone is disclosed in WO 0239783. The microphone comprises a microphone array having a plurality of microphone elements of which one element is a rear element and the other elements are forward elements. A processor is connected to the elements. The processor can be a hardware processor for processing signals or it can be a software controlled system for processing signals. The processor determines the arrival of a wave at one of the forward elements and thereafter establishes a window of opportunity for receipt of the wave at the rear element.
The window of opportunity is set such that only waves emanating from a particular direction will arrive in that time frame, thereby enabling acoustic waves from that direction to be processed by the microphone and other waves from different directions eliminated. The angle of arc of the microphone from which acoustic waves are received and processed can be set by changing the size of the window of opportunity t3−t2. In the hardware implementation, the processor includes filters, zero cross-over detectors, monostables and a flip-flop for setting a timing signal and triggering the flip-flop to control the switch so that if a wave does arrive at the element within the bandwidth of the filters, an audio signal corresponding to the wave is transmitted from the element through the switch to an output.
A method of estimating weighting function of audio signals in a hearing aid is disclosed in US 2009202091. The method includes estimating a weighting function of received audio signals, the hearing aid is adapted to be worn by a user; the method comprises the steps of: estimating a directional signal by estimating a weighted sum of two or more microphone signals from two or more microphones, where a first microphone of the two or more microphones is a front microphone, and where a second microphone of the two or more microphones is a rear microphone; estimating a direction-dependent time-frequency gain, and synthesizing an output signal; wherein estimating the direction-dependent time-frequency gain comprises: obtaining at least two directional signals each containing a time-frequency representation of a target signal and a noise signal; and where a first of the directional signals is defined as a front aiming signal, and where a second of the directional signals is defined as a rear aiming signal; using the time-frequency representation of the target signal and the noise signal to estimate a time-frequency mask; and using the estimated time-frequency mask to estimate the direction-dependent time-frequency gain.
Systems and methods of detecting a user's voice activity using an accelerometer are disclosed in WO 2014051969 and US 2014270231. The methods start with a voice activity detector (VAD) generating a VAD output based on (i) acoustic signals received from microphones included in the mobile device and (ii) data output by an inertial sensor that is included in an earphone portion of the mobile device. The inertial sensor may detect vibration of the user's vocal chords modulated by the user's vocal tract based on vibrations in bones and tissue of the user's head. A noise suppressor may then receive the acoustic signals from the microphones and the VAD output and suppress the noise included in the acoustic signals received from the microphones based on the VAD output. The method may also include steering one or more beamformers based on the VAD output.
A three-dimensional sound compression and over-the-air-transmission method during a call is disclosed in WO 2013176959. A wireless communication device records a plurality of directional audio signals. The wireless communication device also generates a plurality of audio signal packets based on the plurality of directional audio signals. At least one of the audio signal packets includes an averaged signal. The wireless communication device further transmits the plurality of audio signal packets.
A headset and a method for audio signal processing is disclosed in EP2884763. The headset comprises a first pair of microphones outputting a first pair of microphone signals and a second pair of microphones outputting a second pair of microphone signals; a first near-field beamformer and a second near-field beamformer each configured to receive a pair of microphone signals and adapt the spatial sensitivity of a respective pair of microphones as measured in a respective beamformed signal output from a respective beamformer, wherein the spatial sensitivity is adapted to suppress noise relative to a desired signal; a third beamformer configured to dynamically combine the signals output from the first beamformer and the second beamformer into a combined signal, wherein the signals are combined such that signal energy in the combined signal is minimized while a desired signal is preserved; and a noise reduction unit configured to process the combined signal from the third beamformer and output the combined signal such that noise is reduced.
A method for three-dimensional sound capturing and reproducing with multi-microphones is disclosed in WO 2012061151. The method of orientation-sensitive recording control includes indicating, within a portable device and at a first time, that the portable device has a first orientation relative to a gravitational axis and, based on the indication, selecting a first pair among at least three microphone channels of the portable device. This method also includes indicating, within the portable device and at a second time that is different than the first time, that the portable device has a second orientation relative to the gravitational axis that is different than the first orientation and, based on the indication, selecting a second pair among the at least three microphone channels that is different than the first pair. In this method, each of the at least three microphone channels is based on a signal produced by a corresponding one of at least three microphones of the portable device.
A Bluetooth microphone array is disclosed in U.S. Pat. No. 8,295,771. Signal processing resources of a wireless telephone and multi-channel transmission capabilities of the Bluetooth transmission are used to suppress the background noise. The wireless telephone system includes a Bluetooth transceiver communicating to a wireless telephone through a multi-channel Bluetooth transmission, and an array of microphones coupled to the Bluetooth transceiver. The array of microphones includes a first microphone producing a first audio signal output and a second microphone producing a second audio signal output. The first audio signal output and second audio signal output are transmitted to the wireless telephone through the first channel and second channel of multi-channel Bluetooth transmission respectively. The system and method of the invention allow using low cost Bluetooth transceiver(s) with multiple microphone arrays to provide the background noise suppression. There are numerous other known devices and methods in the art. The following references are exemplary: WO 2012061151; CN 202998463; US 2012020485; US 2015245129; US 2012087510; U.S. Pat. No. 6,594,370; US 2011293103; US 2011317858; WO 2005094157; EP 2736272; US 2013101136; US 2015049892; US 2010131269; U.S. Pat. No. 4,751,738; U.S. Pat. No. 5,737,430; U.S. Pat. No. 5,563,951; U.S. Pat. No. 5,757,929; WO 2004028203; U.S. Pat. No. 6,424,721; U.S. Pat. No. 9,202,455.
However, no relevant information has been found on defining an optimized microphone layout in an array, based on peculiarities of the sound waves generated by a speaking user and propagating in the area of the user's head. Thus, the inventor performed extensive research works in order to define an advantageous microphone layout in a microphone array, which allowed him building an advanced model for implementing principles described in his earlier publication [9]. Further development of these principles ensured the inventions set forth in the following description and drawings.